有效剪切面积对直剪试验结果的影响分析

Effect of effective shearing area on result of direct shear tests

我国现行土工试验的国家标准和行业规程中,对于直剪试验数据的整理和分析均未考虑剪切过程中土体本身或土体与其他材料接触面上剪切面积的变化.为此,推导了剪切过程中接触面剪切位移与有效剪切面积之间的关系,分析了现行数据整理方法引起的计算误差.结果表明,现行数据整理方法低估了土体或土体与其他材料接触面上的剪切应力和抗剪强度指标;直剪试验的剪切方向应沿着试样盒的长边方向布置.

In the existing national standard and specification for geotechnical test in China, the variation of shearing areas of soil body and the interface between soil body and other materials during the sheafing process was not taken into account in the interpretation of direct shear test data. For this reason, the relationship between the shear displacement and the effective shearing area of the interface during the shearing process was deduced, and the errors induced by the existing data interpretation method were analyzed. The result shows that the existing method underestimates the shear stress and shear strength parameter of soil body and the interface between soil body and other materials, and that the shearing direction in the direct shear test is preferred to be along the long side of the shear box.